The present invention relates to the field of semiconductor structures, and particularly to a decoupling capacitor that employs a conductive through-substrate via and methods of manufacturing the same.
In resent years, “three dimensional silicon” (3DSi) structures have been proposed to enable joining of multiple silicon chips and/or wafers that are mounted on a package or a system board. The 3DSi structures increase the density of active circuits that are integrated in a given space.
As the circuit density increases unit area, the amount of switching activity per unit area also increases. This results in an increase in the noise generated on the reference supplies. As this noise increases, the performance of the internal devices as well as the performance of off-chip drivers is adversely impacted due to the reduction of noise margins available for the system design.
At present, this noise is controlled by embedding deep trench capacitors (DTC) within active silicon devices. To obtain sufficient degree of decoupling, a large array of DTC's are required. As the circuit density, switching activity, and power distribution structures are enhanced in a 3DSi structure, more DTC's will be required to control the noise generation. Further, as a number of DTC arrays are formed, there is an increase in the inductance between the active circuits and the arrays of DTC's, thereby requiring formation of additional DTC's to store the energy to be used to counter-balance a back electromagnetic force noise.
The voltage of the noise Vn is given by the following equation:Vn=L×(dI/dt),in which L is inductance, I is current, and t is time. As the amount of inductance (L) increases, or as the speed at which the current changes (dI/dt), which is proportional to the switching speed of circuits, the noise Vn increases proportionally.
The above considerations show that capacitive structures having low inductive is needed to control inductively noise generated within and transmitted into a 3DSi structure.